Respiratory support systems are commonly used to support the respiratory system of a critically ill patient for maintaining optimal blood oxygen levels, as well as optimal carbon dioxide levels and acid base balance. Typically, a prior art respiratory support system includes a tracheal tube, positioned either directly through the nose or mouth into the trachea of a patient. A multi-ported manifold is connected to the endotracheal tube at one port position, and a source of breathable gas is connected at a second port. The respiratory support system assists the patient in maintaining adequate blood oxygenation levels without overtaxing the patient's heart and lungs.
While a patient is attached to the respiratory support system, it is periodically necessary to aspirate fluids and or secretions from the patient's trachea and lungs. In the past, in order to accomplish aspiration and positive pressure ventilation, it was necessary to disassemble part of the respiratory support system, either by removing the ventilator manifold or by opening a port thereof and inserting a small diameter suction tube down the tracheal tube and into the patient's trachea and lungs. The fluid was then suctioned from the patient and the suction catheter was removed and the respiratory support system reassembled. However, due to the interruption of respiratory support during this procedure, a patient's blood oxygen can often drop and the carbon dioxide can change to unacceptable levels. Additionally, unless a sufficient positive end expiratory pressure (PEEP) level is maintained, then the lungs might collapse. This creates a dangerous condition for the patient because the lungs can be difficult, and sometimes impossible, to reinflate.
Patients may have fluid drawn from their lungs as often as six times a day and sometimes more, possibly over long periods of time. For this reason, it is critical to provide a respiratory device which will minimize patient discomfort. In addition, such a device could be widely used in treating pediatric patients, especially premature infants, as well as adults, who are subject to respiratory problems and may need frequent aspirations. As a result of the extremely large number of aspirations necessary on various patients in any period, it is important that the price of the respiratory device be as low as possible since vast numbers will be used. It is also important that the device be sufficiently inexpensive so that it may be discarded after a single use. Hence, it is desirable to simplify such devices and reduce the number of parts in order to reduce costs and increase reliability.
U.S. Pat. No. 5,746,199 to Bayron et al teaches a rotary valve with multiple ports, any two of which can be aligned with openings in the casing to provide through passages for delivering breathable gases to an endotracheal tube. The valve has a handle that cooperates with detents on the casing to secure the position of the rotary valve. However, any catheter inserted and removed through the endotracheal tube and valve ports that are connected with the ventilation ports provides a contact pathway for infectious organisms to the ventilators.
The manufacture of this rotary valve, as well as the other rotary valves mentioned here, requires precise control of the circular tolerances of the rotary valve and casing to prevent leakage around the valve. Such safety concerns increase the costs of manufacture and quality control measures.
Other prior art devices have attempted to maintain a continuous flow of oxygen from the respirator device through to the lungs, while allowing for insertion and retraction of the suction catheter. However, such devices fail to provide an operable system capable of performing both manual and machine assisted respiration without disconnecting the respirator. Manual respiration with a resuscitation bag during suction is a preferred method among many practitioners because it optimizes removal of fluids in the lungs while maintaining PEEP and maintaining cardiopulmonary and hemodynamic balance. U.S. Pat. No. 4,351,328 discloses a device for simultaneous respiration and endotracheal suctioning of a critically ill patient. This device requires a specialized sealing port for insertion and retraction of the suction catheter to maintain the integrity of the respiration system. While machine assisted respiration is occurring, no switchover to manual resuscitation methods is provided.
U.S. Pat. No. 5,343,857 discloses an accessory port capable of receiving a specially designed male adaptor on a suction catheter. The accessory port consists of a normally closed valve which is forced open by the male adaptor, and returns to its closed position upon retraction of the adaptor. The adaptor sealably interacts with the accessory port so as to inhibit pressure loss from the manifold. A similar device is disclosed in U.S. Pat. No. 5,309,902.
As detailed in the background discussions of these prior art disclosures, there are many difficulties associated with maintaining continuous pressure from the respiration supply device. More particularly, it is often desirable to be able to manually inflate the lungs with a resuscitation bag at different rates and different volumes in order to facilitate complete aspiration of mucous and liquid from the lungs. With the extra “hands-on” control offered by the resuscitation bag, a doctor or technician can simulate expectory coughing actions and the like through quick inflation and deflation bursts. Moreover, PEEP can be easily maintained with the resuscitation bag, while the suction catheter is repeatedly inserted and retracted from the lungs as needed.
Other interface devices require the respirator source to be disconnected in order to attach the desired resuscitation bag. Once aspiration is complete, this presents a problem with maintaining PEEP when the resuscitation bag is disconnected and the respirator source is reconnected. Even if performed in a timely and efficient manner, this switchover operation can jeopardize the patient's life if PEEP is not maintained. Hence, it is important to minimize this switchover time, while also providing for attachment of the resuscitation bag. Other devices remain connected to the respirator source and do not allow for use of a resuscitation bag.
U.S. Pat. No. 5,207,641 discloses a switching device with a rotary valve having aspiration, insufflation, and intermediate flushing positions. An oxygen port and suction port are included with a catheter port. These ports allow suction and insufflation to alternately occur through the continuously inserted catheter, without withdrawal of the catheter tube from the lungs. While providing a neutral valve position, this arrangement might still encounter problems such as blow-back of mucous through the inserted catheter, and/or clogging of the valve parts by suctioned mucous.
U.S. Pat. No. 3,780,736 discloses a surgical valve assembly for urinary bladder irrigation and drainage. This valve has four ports and provides a core for interconnecting any two of the four ports. The core allows irrigation fluids to flow from one port to another, but the '736 device does not disclose a valve for introduction and withdrawal of a suction catheter through the device in either of two switched positions, and the '736 device does not disclose ports for receiving air from a respirator in one switched position or alternatively from a resuscitation bag in the other switched position.
Given the frequent insertion and withdrawal of the suction catheter, a protective bag, or sleeve, would also be a useful addition to existing suction catheter devices. This bag would prevent external contact with the catheter thereby maintaining a sterile device for reinsertion into the patient. U.S. Pat. No. 5,073,164 discloses a specialized catheter which incorporates a protective sleeve. A bag which can be sealably attached around any existing suction catheter would be even more versatile than the incorporated sleeve.
Accordingly, what is lacking in the art is a compact, inexpensive, improved, simplified respiratory device which can accommodate the introduction of a catheter into a patient's lungs separated from the respiratory valve while maintaining connection with an external respirator source, and which will subsequently allow uninterrupted respiratory switchover to a resuscitation bag to maintain optimal ventilation.